Regolith migration and sorting on asteroid Itokawa

High-resolution images of the surface of asteroid Itokawa from the Hayabusa mission reveal it to be covered with unconsolidated millimeter-sized and larger gravels. Locations and morphologic characteristics of this gravel indicate that Itokawa has experienced considerable vibrations, which have triggered global-scale granular processes in its dry, vacuum, microgravity environment. These processes likely include granular convection, landslide-like granular migrations, and particle sorting, resulting in the segregation of the fine gravels into areas of potential lows. Granular processes become major resurfacing processes because of Itokawa's small size, implying that they can occur on other small asteroids should those have regolith.     

Transfer factor of radioactive cesium to forage corn (Zea mays L.) from soil to which contaminated farmyard manure had been applied

Abstract

Radioactive cesium (Cs) deposited after the Fukushima Daiichi Nuclear Power Station accident contaminated farmyard manure (FYM) in the wide area surrounding the plant. We conducted a field trial to determine the transfer factor of radioactive Cs to forage corn (Zea mays L.) from soil to which the contaminated FYM had been applied. The main purpose of this experiment was to examine the behavior of the radioactive Cs from contaminated FYM that was incorporated in agricultural fields. Application of FYM containing 3900 Bq kg^?1 dry matter (DM) of cesium-137 (¹³⁷Cs) at a rate of 4.3 kg m^?2 increased the ¹³⁷Cs concentration in the soil by 64 Bq kg^?1 dry soil, and in the forage corn by 9.2 Bq kg^?1 DM. Therefore, we calculated the transfer factor to corn plants from the soil after application of contaminated FYM to be 0.14. This value is lower than that observed for soil to which uncontaminated FYM had been applied as a control, and it is within the range of reported soil-to-plant transfer factors of 0.003–0.49 listed in the recent parameter handbook by International Atomic Energy Agency. The increase in the radioactive Cs concentration in the corn plants, expressed as the sum of ¹³⁷Cs and cesium-134 (¹³⁴Cs), was only 3% of the 2012 provisional tolerance level for cattle roughage in Japan. Even though the application of contaminated FYM did not cause a large change in the radioactive Cs concentration in the corn plants in this trial, such application should be carefully controlled because it increased radioactive Cs concentrations in both soil and forage corn.     

Irradiation history of Itokawa regolith material deduced from noble gases in the Hayabusa samples

Noble gas isotopes were measured in three rocky grains from asteroid Itokawa to elucidate a history of irradiation from cosmic rays and solar wind on its surface. Large amounts of solar helium (He), neon (Ne), and argon (Ar) trapped in various depths in the grains were observed, which can be explained by multiple implantations of solar wind particles into the grains, combined with preferential He loss caused by frictional wear of space-weathered rims on the grains. Short residence time of less than 8 million years was implied for the grains by an estimate on cosmic-ray-produced (21)Ne. Our results suggest that Itokawa is continuously losing its surface materials into space at a rate of tens of centimeters per million years. The lifetime of Itokawa should be much shorter than the age of our solar system.     

Development of photoperiod-sensitive cytoplasmic male sterile (PCMS) wheat lines showing high male sterility under long-day conditions and high seed fertility under short-day conditions

A “two-line system” using photoperiod-sensitive cytoplasmic male sterility (PCMS) caused by Aegilops crassa cytoplasm under long-day photoperiods (≧15 h) has been proposed as a means of producing hybrid varieties in common wheat (Triticum aestivum). The PCMS line is maintained by self-pollination under short-day conditions, and hybrid seeds can be produced through outcrossing of the PCMS line with a pollinator line under long-day conditions. Our previous studies revealed that PCMS lines showing complete male sterility under long-day conditions are necessary for practical hybrid wheat breeding, especially to obtain high hybrid purity in F₁ seeds. Furthermore, practical PCMS lines should have high seed fertility under short-day conditions, which is associated with female fertility. Wheat cv. Norin 26 with Ae. crassa cytoplasm exhibits high seed fertility under short-day conditions, and cv. Fujimikomugi with Ae. crassa cytoplasm shows high male sterility under long-day conditions. Here we developed practical PCMS lines derived from the F₁ generation of Norin 26 and Fujimikomugi (with Ae. crassa cytoplasm) that were then backcrossed to elite wheat lines.     

Identification of marker genes for intestinal immunomodulating effect of a fructooligosaccharide by DNA microarray analysis

Prebiotic fructooligosaccharides are noted for their intestinal immunodulating effects, and the identification of markers for the effects is a matter of great concern. This study aimed to identify marker genes for physiological effects of a particular fructooligosaccharide (FOS) on a host animal and also to define the target of its function in the small intestine. DNA microarray technology was used to screen candidate marker genes, and comprehensive changes in gene expressions in the ileum of mice fed with FOS were investigated. One of the major physiological effects of FOS was intestinal immunomodulation. Marker genes were then identified for major histocompatibility complex classes I and II, interferon, and phosphatidylinositol metabolites. Also, the ileum was segmented into Peyer's patch (PP) and the other ileal organ (DeltaPP), and these were analyzed by quantitative RT-PCR method, with the result that the site for recognizing the FOS function was the DeltaPP rather than the PP. This is the first paper showing the markers for the physiological effects of FOS in the small intestine at gene expression level. Applying these marker genes would make it possible to clarify the mechanisms of how the administration of dietary FOS and associated changes in the intestinal environment are recognized by host organisms as well as how its immunomodulating effects are expressed in the body.     

Detection of antifungal activity in Anemarrhena asphodeloides by sensitive BCT method and isolation of its active compound

Antifungal activity was detected from Anemarrhena asphodeloides by the Bio-Cell Tracer (BCT) method. An active fraction was separated by silica gel column chromatography and reverse-phase HPLC. The molecular weight was determined by GC-MS, and the molecular structure was analyzed by IR, (1)H NMR, and (13)C NMR. The isolated compound was found to be identical to nyasol, (Z)-1, 3-bis(4-hydroxyphenyl)-1,4-pentadiene, which formerly appeared in the literature without any remark on the antifungal activity. This compound showed antimicrobial activity against 38 strains of fungi and five strains of bacteria. The minimum inhibitory concentration (MIC) ranged from 12.5 to 200 microg mL(-)(1), except for two strains based on the broth dilution method.     

Selection of cowpea genotypes based on grain mineral and total protein content

Grain legumes, including cowpea, are the cheapest sources of minerals and protein to enhance human nutrition. Cultivar development and deployment of cowpea with increased grain mineral content and protein composition rely on selection of genetically unique and complementary breeding lines. The objective of this study was to assess the grain minerals and protein composition of diverse cowpea collections of eastern, southern and western Africa to select promising parents to develop a breeding population. Twenty-two genetically diverse cowpea genotypes were field evaluated using a randomised complete block design with three replications in two locations in South Africa. The dried grain mineral contents were determined using an Atomic Absorption Spectrophotometre, while the protein content was determined by the combustion method. Analyses of variance showed significant (P?<?0.05) effects of genotypes, locations and their interactions. The test genotypes showed considerable variation for the following nine mineral contents: calcium (Ca), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), phosphorus (P), and zinc (Zn) varying from 0.07 to 0.12?mg?kg^?1; 4.46 to 7.81?mg?kg^?1; 0.06 to 0.11?g; 11.82 to 14.45?g; 1.86 to 2.27?g; 9.24 to 13.30?mg?kg^?1; 0.26 to 0.80?g; 4.63 to 5.92?g and 0.03.00 to 0.05?g, respectively. Further, the total protein content varied from 23.16 to 28.13%. Significant correlations were detected among some mineral elements and total protein content, suggesting the possibility of simultaneous selection for these traits. The principal component analysis (PCA) identified four principal components (PCs) contributing to 70.93% of the total explained variation amongst genotypes. Overall the following genotypes with desirable grain mineral and protein attributes were selected: IT90K-59 (Ca), 98K-5301 (Ca and protein), ITOOK-1060 (Cu), ITOOK-1217 and IT845-2246 (Fe), Bensogla (K, Na, and P), TVU11424 and ITOOK-1217 (Mg), CH14 (Mn and Na), TVU12637 (Mn) and Glenda and Vuli (Zn). The selected cowpea genotypes are useful genetic resources for population and cultivar development for grain nutrients composition.     

Evaluation of plant bed filter ditches for the removal of T-N and T-P from eutrophic pond water containing particulate N and P

Cultivation of useful terrestrial and aquatic plant species in plant bed filter ditches enables to treat domestic wastewater in addition to resource recycling and amenity functions. We reported previously that a ditch planted with papyrus removed Nand P most effectively from artificial wastewater. We evaluated the effectiveness of plant bed filter ditches in the treatment of eutrophic pond water, which unlike artificial wastewater, contains particulate Nand P. Experimental ditches were planted with papyrus, African marigold, peppermint, and impatience. These plant species were effective in removing N and P from artificial wastewater and could be used by rural communities for the production of handicrafts, cut flowers, and ornamental purposes. The control ditch did not contain plants (plant-free ditch). Pond water was continuously supplied to the ditches at a loading rate of 0.6–0.9 g m^-2 d^-1 for Nand 0.2–0.35 g m^-2 d^-1 for P. In the plant-free ditch, particulate Nand P in the influent were removed by passage through the bed filter, unlike NO³-N and PO⁴-P. A larger amount of PO⁴-P was dissolved from particulate P in the bed filter. The planted ditches effectively removed NO³-N, PO⁴-P as well as particulate Nand P. The planted ditches were able to purify eutrophic pond water, resulting in clear water with a concentration below 0.3 mg L^-1 for N and 0.02 mg L^-1 for P, concentrations at which water bloom does not occur. The average removal rate of pollutants by the planted ditches during the experiment, except for the first 2 weeks, was 0.67 g m^-2 d^-1 for total N and 0.03 g m^-2 d^-1 for total P. We recommend that plant bed filter ditches containing papyrus and flowers be used for ornamental purposes and removal of N and P from pond water along with the supply of clear water as ornamental streams.     

Plant seed cystatins and their target enzymes of endogenous and exogenous origin

Cystatins are protein inhibitors of cysteine proteinases of the papain family, and those of animal origin have long been studied from medical and physiological aspects. In the meantime, oryzacystatin cloned from rice seeds in 1987 was recognized as the first well-defined cystatin of plant origin. Cloning studies followed to disclose various plant cytstatins including those of corn and soybean origin, their similarities to and differences from animal cystatins being analyzed in detail. Plant seed cystatins are now understood as factors controlling germination by inhibition of endogenous cysteine proteinases. They can also recognize insect midgut proteinases as exogenous target enzymes to control. This paper discusses chemical and phytophysiological relationships between cystatins and their targets.     

Characterisation of agro-morphological traits of corchorus accessions

The genus Corchorus includes nutrient-rich indigenous leafy vegetables often grown or harvested in the wild in Africa. It has potential to contribute to food security, but there is need to improve it as a crop through plant breeding. However, not much is known about the genetic variability among Corchorus species. The aim of this study was thus to characterise the available germplasm of Corchorus accessions and investigate heritability of their agro-morphological traits. Eleven Corchorus accessions (4 South African and 7 from the World Vegetable Center) were evaluated in a field study at Roodeplaat, South Africa, for their morpho-agronomic traits using a randomised complete block design with three replications across two seasons (2015/2016 and 2016/2017). Data were subjected to ANOVA, principal component analysis and cluster analysis. Broad sense heritability, genetic advance, genetic parameters and correlations were determined among the accessions and traits. The Corchorus accessions showed significant (P < .05) differences in all the quantitative traits evaluated. The data showed significant variability among the studied Corchorus accessions in their agro-morphological traits for exploitation in future breeding programmes that in turn can contribute to the improvement of this crop.